Methods of forming semiconductor devices, assemblies and constructions

ABSTRACT

Embodiments disclosed herein include methods in which a pair of openings are formed into semiconductor material, with the openings being spaced from one another by a segment of the semiconductor material. Liners are formed along sidewalls of the openings, and then semiconductor material is isotropically etched from bottoms of the openings to merge the openings and thereby completely undercut the segment of semiconductor material. Embodiments disclosed herein may be utilized in forming SOI constructions, and in forming field effect transistors having transistor gates entirely surrounding channel regions. Embodiments disclosed herein also include semiconductor constructions having transistor gates surrounding channel regions, as well as constructions in which insulative material entirely separates an upper semiconductor material from a lower semiconductor material.

TECHNICAL FIELD

The technical field is semiconductor devices, assemblies andconstructions, and methods of forming semiconductor devices, assembliesand constructions.

BACKGROUND

A continuing goal of semiconductor device fabrication is to conservesemiconductor wafer real estate (in other words, to achieve highintegration) while maintaining integrity and desired performancecharacteristics of semiconductor devices. Such has led to developmentand improvement of various semiconductor constructions, including, forexample, silicon-on-insulator (SOI) constructions, and fin field effecttransistors (finFETs).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic, cross-sectional, fragmentary view of asemiconductor construction at a preliminary processing stage of anembodiment.

FIG. 2 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 1.

FIG. 3 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 2.

FIG. 4 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 3.

FIG. 5 is a view of the FIG. 1 fragment shown at a processing stagesubsequent to that of FIG. 4.

FIGS. 6 and 7 are a top view and cross-sectional side view,respectively, of a fragment of a semiconductor construction shown at apreliminary processing stage in accordance with another embodiment. Thecross-section of FIG. 7 is along the line 7-7 of FIG. 6.

FIGS. 8 and 9 are views of the fragments of FIGS. 6 and 7, respectively,shown at a processing stage subsequent to that of FIGS. 6 and 7. Thecross-section of FIG. 9 is along the line 9-9 of FIG. 8.

FIGS. 10 and 11 are views of the fragments of FIGS. 6 and 7,respectively, shown at a processing stage subsequent to that of FIGS. 8and 9. The cross-section of FIG. 11 is along the line 11-11 of FIG. 10.

FIGS. 12-14 are views of the semiconductor construction of FIGS. 6 and 7shown at a processing stage subsequent to that of FIGS. 10 and 11. FIGS.12 and 13 correspond to the views of FIGS. 6 and 7, respectively, andFIG. 14 corresponds to a view approximately orthogonal to that of FIG.13. The cross-section of FIG. 13 is along the lines 13-13 of FIGS. 12and 14; and the cross-section of FIG. 14 is along the lines 14-14 ofFIGS. 12 and 13.

FIGS. 15-17 are views of the semiconductor construction of FIGS. 6 and 7shown at a processing stage subsequent to that of FIGS. 12-14; with thefragments of FIGS. 15-17 corresponding to the fragments of FIGS. 12-14,respectively. The cross-section of FIG. 16 is along the lines 16-16 ofFIGS. 15 and 17; and the cross-section of FIG. 17 is along the lines17-17 of FIGS. 15 and 16.

FIGS. 18-20 are views of the semiconductor construction of FIGS. 6 and 7shown at a processing stage subsequent to that of FIGS. 15-17; with thefragments of FIGS. 18-20 corresponding to the fragments of FIGS. 12-14,respectively. The cross-section of FIG. 19 is along the lines 19-19 ofFIGS. 18 and 20; and the cross-section of FIG. 20 is along the lines20-20 of FIGS. 18 and 19.

FIGS. 21-23 are views of the semiconductor construction of FIGS. 6 and 7shown at a processing stage subsequent to that of FIGS. 18-20; with thefragments of FIGS. 21-23 corresponding to the fragments of FIGS. 12-14,respectively. The cross-section of FIG. 22 is along the lines 22-22 ofFIGS. 21 and 23; and the cross-section of FIG. 23 is along the lines23-23 of FIGS. 21 and 22.

FIGS. 24-27 are a top view and cross-sectional side views of a fragmentof a semiconductor construction shown at a preliminary processing stagein accordance with another embodiment. The cross-section of FIG. 25 isalong the lines 25-25 of FIGS. 24 and 27; the cross-section of FIG. 26is along the lines 26-26 of FIGS. 24 and 27; and the cross-section ofFIG. 27 is along the lines 27-27 of FIGS. 24-26.

FIGS. 28-31 are views of the fragments of FIGS. 24-27, respectively,shown at a processing stage subsequent to that of FIGS. 24-27. Thecross-section of FIG. 29 is along the lines 29-29 of FIGS. 28 and 31;the cross-section of FIG. 30 is along the lines 30-30 of FIGS. 28 and31; and the cross-section of FIG. 31 is along the lines 31-31 of FIGS.28-30.

FIGS. 32-35 are views of the fragments of FIGS. 24-27, respectively,shown at a processing stage subsequent to that of FIGS. 28-31. Thecross-section of FIG. 33 is along the lines 33-33 of FIGS. 32 and 35;the cross-section of FIG. 34 is along the lines 34-34 of FIGS. 32 and35; and the cross-section of FIG. 35 is along the lines 35-35 of FIGS.32-34.

FIGS. 36-39 are views of the fragments of FIGS. 24-27, respectively,shown at a processing stage subsequent to that of FIGS. 32-35. Thecross-section of FIG. 37 is along the lines 37-37 of FIGS. 36 and 39;the cross-section of FIG. 38 is along the lines 38-38 of FIGS. 36 and39; and the cross-section of FIG. 39 is along the lines 39-39 of FIGS.36-38.

FIG. 40 is a top view of a semiconductor wafer fragment illustratinganother embodiment.

FIG. 41 is a diagrammatic view of a computer embodiment.

FIG. 42 is a block diagram showing particular features of themotherboard of the FIG. 41 computer embodiment.

FIG. 43 is a high level block diagram of an electronic systemembodiment.

FIG. 44 is a simplified block diagram of a memory device embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure is submitted in furtherance of the constitutionalpurposes of the U.S. Patent Laws “to promote the progress of science anduseful arts” (Article 1, Section 8).

In some embodiments, a pair of openings are formed in a semiconductormaterial, with such openings being spaced from one another by a segmentof the semiconductor material. Liners are then formed along sidewallsthe openings, and the semiconductor material is isotropically etchedfrom bottoms of the lined openings to merge the openings and therebycompletely undercut the segment of semiconductor material. Suchembodiments may be utilized for forming three-dimensional structures insilicon, and may be applied toward fabrication of SOI structures andfully surrounded transistor structures (in other words, transistorshaving gates encircling a channel region).

A first embodiment is described with reference to FIGS. 1-5.

Referring initially to FIG. 1, a semiconductor construction 10 isillustrated at a preliminary processing stage. Construction 10 comprisesa base 12 containing semiconductor material. In some embodiments, base12 may be a silicon wafer, and may comprise, consist essentially of, orconsist of monocrystalline silicon lightly-doped with background p-typedopant. The base 12 may be referred to as a semiconductor substrate. Toaid in interpretation of the claims that follow, the terms“semiconductive substrate” and “semiconductor substrate” are defined tomean any construction comprising semiconductive material, including, butnot limited to, bulk semiconductive materials such as a semiconductivewafer (either alone or in assemblies comprising other materialsthereon), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductive substrates described above.

A pair of masking materials 11 and 14 are over substrate 12, andpatterned to have a pair of openings 16 and 18 extending therethrough.Material 11 may, for example, consist of photolithographically patternedphotoresist; and material 14 may comprise one or both of silicon nitrideand silicon dioxide. The pattern in material 14 can be formed bytransferring a pattern from photolithographically patterned resist 11into an underlying layer of material 14 with one or more etches.

Referring to FIG. 2, openings 16 and 18 are extended into base 12 withan appropriate etch. Such etch is shown to be an anisotropic etch (suchas, for example, an etch using Cl₂ and HBr), and specifically to bedirected primarily downwardly into base 12. The openings within base 12have a periphery comprising bottoms 15 and sidewalls 17. It is notedthat the openings would have backside surfaces behind the plane of FIG.2 that would be visible in the view of FIG. 2. However, in order tosimplify the drawings, only surfaces along the plane of a cross-sectionwill be shown in the cross-sectional views presented herein.

The openings 16 and 18 within base 12 may be considered to be a pair ofopenings which are spaced from one another by a segment 20 of thesemiconductor material of base 12. The segment 20 comprises a width 21between the openings 16 and 18. Such width may be, for example, fromabout 10 nanometers to about 350 nanometers.

Referring to FIG. 3, photoresist 11 (FIG. 2) is removed, and liners 22are formed along exposed sidewalls 17 of the openings 16 and 18 withinbase 12. The photoresist can be removed in a reaction chamber utilizingan O₂ plasma. The liners can be formed in the same chamber as is usedfor removing of the photoresist, and utilizing the O₂ plasma; but thesubstrate may be biased differently for formation of the liners than forremoval of the photoresist. If base 12 corresponds to a monocrystallinesilicon wafer, liners 22 may comprise, consist essentially of, orconsist of silicon dioxide. Such silicon dioxide would extend acrossbottoms of the openings, as well as along the sidewalls, but may besubsequently removed from the bottoms with an appropriate etch to leavethe liners only along the sidewalls. Liners 22 may be referred to asprotective material, in that the liners protect sidewalls 17 from asubsequent etch. Liners 22 narrow openings 16 and 18 relative to theinitial widths of the openings.

Referring to FIG. 4, an isotropic etch is conducted to extend openings16 and 18 into base material 12. Liners 22 protect sidewalls ofuppermost regions of the openings during such isotropic etching. Theisotropic etching forms bowls (or bulbous regions) 24 at lower portionsof the openings. Any suitable isotropic etching conditions may beutilized, and the etch may, for example, comprise NF₃.

Referring to FIG. 5, the isotropic etching is continued until openings16 and 18 merge under segment 20, and thus completely undercut suchsegment. In subsequent processing, masking material 14 may be removed,and the openings 16 and 18 may be filled with material having desiredelectrical properties to form a desired construction. For instance, theopenings 16 and 18 may be filled with electrically insulative material(such as, for example, silicon dioxide) to form an SOI constructionhaving the semiconductor of segment 20 over the insulator of the fillmaterial. As another example, semiconductor material of segment 20 maybe doped to form a channel between a pair of source/drain regions, andopenings 16 and 18 may be filled with transistor gate material.

Referring to FIGS. 6 and 7, such illustrate a semiconductor construction50 at a preliminary processing stage of an embodiment for forming SOIstructures.

Construction 50 comprises a semiconductor base 12 which may, forexample, correspond to the monocrystalline silicon wafer discussed abovewith reference to the embodiment of FIGS. 1-5. Construction 50 alsocomprises masking material 14.

A plurality of active area locations 52, 54, 56, 58, 60, 62, 64, 66, 68,70, 72, 74, 76, 78, 80 and 82 are defined within semiconductor materialof base 12, and such locations are approximately demarcated with dashedlines. The active area locations form an array comprising columnsextending substantially vertically relative to the shown array (with anexample column extending along the active area locations 54, 62, 70 and78), and comprising rows extending substantially horizontally relativeto the shown array (with an example row extending along the active arealocations 60, 62, 64 and 66, and accordingly along the cross-section ofFIG. 9). Adjacent active area locations of the rows and columns arespaced from one another by regions of semiconductor material ofsubstrate 12, as shown.

Referring to FIGS. 8 and 9, material 14 is patterned to define locationsfor trenches. Such patterning can be accomplished using aphotolithographically patterned photoresist mask (not shown) which maybe subsequently removed. The pattern of material 14 is transferred tounderlying base 12 to form trenches 90, 92, 94, 96 and 98 betweencolumns of the array of active area locations. Such trenches extend toends of the active area locations (or in other words, join to the endsof the active area locations).

Referring to FIGS. 10 and 11, trenches 90, 92, 94, 96 and 98 are filledwith dielectric material (or in other words, electrically insulativematerial) 100. The dielectric material may comprise any suitablecomposition or combination of compositions, and in some embodiments maycomprise, consist essentially of, or consist of silicon dioxide.Dielectric material 100 may be formed within the trenches by: initiallyproviding the dielectric material within the trenches and entirelyacross an upper surface of material 14; and subsequently subjectingconstruction 50 to planarization (such as, for example,chemical-mechanical polishing) to remove the dielectric material fromover uppermost surfaces of masking material 14 while leaving thedielectric material within the trenches.

The filled trenches may be considered to correspond to lines ofelectrically insulative material 100 extending across substrate 12. Thecombination of such lines with the rows of active area locations definesa lattice across substrate 12. Sections of substrate 12 which do notcontain an active area location may be considered to be at locationsbetween the rows and lines of the lattice, with example sections 102,104, 106, 108, 110, 112, 114, 116, 118, 120, 122, and 124 being labeledin FIG. 10. The sections along a column of the lattice alternate withactive area locations along a column of the array of active arealocations. For instance, the sections 104, 112 and 120 along a column ofthe lattice alternate with active area locations 54, 62, 70 and 78 alonga column of the active area array.

Referring to FIGS. 12-14, a masking material 11 is formed along the rowsof the active area locations 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72,74, 76, 78, 80 and 82 (with the active area locations beingapproximately illustrated in the top view of FIG. 6). The maskingmaterials 11 and 14 together comprise protective material formed overthe active area locations to protect such locations from a subsequentetch. Masking material 11 is shown to extend over the dielectricmaterial within trenches 90, 92, 94, 96 and 98.

Masking material 11 may, for example, correspond to a layer ofphotolithographically patterned photoresist.

The material 14 over sections 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, and 124 remains exposed between the rows of maskingmaterial 11.

Referring to FIGS. 15-17, openings 132 are anisotropically etchedthrough material 14and into sections 102, 104, 106, 108, 110, 112, 114,116, 118, 120, 122, and 124; masking material 11 is removed; andprotective material liners 134 are formed along sidewalls of theopenings. The openings within base 12 are analogous to the openings 16and 18 discussed above with reference to FIG. 3, and the liners areanalogous to the liners 22 discussed above with reference to FIG. 3. Theopenings 132 and liners 134 may thus be formed with processing similarto that discussed above with reference to FIG. 3, and such processingcan also remove material 11 as discussed above regarding FIG. 3. Theprotective material liners 134 narrow openings 132 in a manner analogousto the above-discussed narrowing of openings 16 and 18 by liners 22.

The openings 132 alternate with active area locations along the columnsof the active area location array in the same manner that the sections102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, and 124 alternatewith such active area locations.

Referring to FIGS. 18-20, openings 132 are extended into basesemiconductor material 12 with an isotropic etch similar to thatdiscussed above with reference to FIGS. 4 and 5. Adjacent openings 132merge beneath active area locations 52, 54, 56, 58, 60, 62, 64, 66, 68,70, 72, 74, 76, 78, 80 and 82 (with the active area locations beingapproximately illustrated in the top view of FIG. 6, and alsoapproximately illustrated in the cross-sections of FIGS. 19 and 20) toform extended openings which are entirely around such active arealocations. The lines of dielectric material 100 within trenches 90, 92,94, 96 and 98 anchor the ends of the active area locations at theprocessing stage of FIGS. 18-20.

Referring to FIGS. 21-23, openings 132 are filled with electricallyinsulative material 140, and material 14 is removed. The material 140may initially be formed to fill the openings and extend over material14, and subsequently planarization (for instance, chemical-mechanicalpolishing) may be used to remove materials 140 and 14 from across someregions of substrate 12. Alternatively, planarization may be used toremove material 140 from over material 14, and then material 14 may beremoved with an etch selective for material 14 relative to material 140(with the term “selective” meaning that the etch removes material 14 ata faster rate than the etch removes material 140). Such alternativeprocessing may leave projections of material 140 (not shown) adjacentthe active area locations.

Material 140 may comprise any suitable composition or combination ofcompositions, but preferably comprises a substance which may be readilyflowed within the openings. Material 140 may, for example, comprise,consist essentially of, or consist of spin on dielectric (i.e.,dielectric material flowable at particular temperature ranges); and maycomprise, consist essentially of, or consist of silicon dioxide.

Dielectric materials 100 and 140 may be referred to as first and seconddielectric materials, respectively. Such dielectric materials maycomprise the same composition as one another in some embodiments.

In the shown embodiment, dielectric material 140 is within the openings,and not across an upper surface of active area locations 52, 54, 56, 58,60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80 and 82.

Dielectric material 140 entirely separates semiconductor material 12within the active region locations from the remaining semiconductormaterial 12 of the base, as may be seen in the cross-sections of FIGS.22 and 23.

Spacers 134 are shown to remain within the openings in combination withdielectric material 140. If spacers 134 and dielectric material 140comprise the same composition as one another, the spacers and dielectricmaterial may merge to form a single insulative material within theopenings. In some applications (not shown) it may be desired to removethe spacers 134 with an appropriate etch prior to provision of material140.

The construction of FIGS. 21-23 comprises a plurality of active areas atlocations 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80 and82; with such active areas being SOI structures. In subsequentprocessing, semiconductor devices may be formed to be associated withthe active areas. For instance, FIGS. 21-23 show a plurality ofwordlines 150, 152, 154, 156, 158, 160, 162, and 164 extending acrossthe active areas. The cross-section of FIG. 22 shows that the wordlinescomprise stacks containing gate dielectric 166, conductive gate material168, and an electrically insulative cap 170. Also, sidewall spacers 172are along sidewalls of the wordlines. A plurality of source/drainregions 180 are provided within the semiconductor material 12 of theactive area locations; and the wordlines together with the source/drainregions form a plurality of transistor devices.

FIG. 21 diagrammatically illustrates capacitors 182, 184, 186, 188, 190,192, 194, and 196 electrically connected to some of the source/drainregions; and also diagrammatically illustrates a bitline 199electrically connected to others of the source/drain regions. Althoughcapacitors and bitline are shown only along the top row of active arealocations to simplify the drawing, it is to be understood thatcapacitors and bitlines would also connect to source/drain regionsassociated with the other active area locations. Persons of ordinaryskill in the art will recognize that the combination of a charge storagedevice (such as a capacitor) with a transistor corresponds to a dynamicrandom access memory (DRAM) unit cell, and accordingly a DRAM array maybe formed across the construction of FIGS. 21-23.

Referring next to FIGS. 24-27, such illustrate a semiconductorconstruction 200 at a preliminary processing stage of an embodiment forforming a field effect transistor.

Construction 200 comprises a base 12 which may be of the samecomposition discussed above regarding FIG. 1, and accordingly maycomprise, consist essentially of, or consist of monocrystalline silicon.

A pair of isolation regions 202 extend into base 12. The isolationregions may comprise any suitable electrically insulative composition orcombination of compositions, and in some embodiments may comprise,consist essentially of, or consist of silicon dioxide.

Patterned masking materials 203 and 204 extend across an upper surfaceof base 12. Such patterned masking materials comprise a narrow region206 between a pair of wide regions 208. The patterned masking materialsmay comprise any suitable composition or combination of compositions.For instance, material 204 may comprise one or both of silicon dioxideand silicon nitride (and may thus be analogous to the material 14discussed with reference to FIG. 1), and material 203 may comprisepatterned photoresist (and may thus be analogous to the material 11discussed with reference to FIG. 1).

The patterned masking materials define a line location 210 thereunderwhich extends within base 12. Specifically, the portion of base 12 underthe masking materials corresponds to such line location. The linelocation thus also comprises the shape of masking materials 203 and 204of a narrow region between a pair of wide regions.

The masking materials 203 and 204, and line defined thereunder, may beconsidered to comprise a pair of opposing sides 212 and 214.

Referring to FIGS. 28-31, trenches 216 are etched into semiconductormaterial of base 12, sidewall liners 218 are formed, and maskingmaterial 203 is removed. The formation of the trenches and liners, andremoval of masking material 203, may be accomplished with processingsimilar to that discussed above with reference to FIGS. 2 and 3.

The trenches 216 may be considered to correspond to a pair of trenches,with one trench of such pair being along side 212 of masking material204, and the other trench of the pair being along side 214 of themasking material. The formation of the trenches 216 transfers thepattern of patterned masking material 204 into the semiconductormaterial of base 12, and accordingly forms a line 211 at the linelocation 210 (FIGS. 24-27). Such line has the opposing sidewalls 212 and214. The line has wide portions and a narrow portion transferred fromthe shape of the mask. In some embodiments, the narrow portion may havea width which is at least about 25% less than the widths of the wideportions.

Sidewall liners 218 are electrically insulative, and may be referred toas protective material. The liners 218 may comprise, consist essentiallyof, or consist of silicon dioxide.

Referring to FIGS. 32-35, openings 216 are extended into base 12 with anisotropic etch analogous to the etch discussed above with reference toFIGS. 4 and 5. The openings from the opposing sides 212 and 214 of line211 merge under narrow portion 206 of the line (as shown in FIG. 34),but do not merge under the wide portions 208 of the line (as shown inFIG. 33). Thus, the narrow portion 206 of the line is thin enough toenable the openings 216 on the opposing sides of the line to mergeduring the isotropic etching, while the wide portions 208 of the lineare sufficiently wide so that the openings do not merge under suchportions. The wide portions 208 thus remain anchored to the bulk of basematerial 12 after the etching under narrow portion 206, and thus theline segment corresponding to narrow portion 206 is retained to the restof construction 200.

Referring to FIGS. 36-39, masking material 204 (FIGS. 32-35) is removed,and dielectric material 220 is formed along exposed portions ofsemiconductor material of base 12. Protective material 218 (FIGS. 32-35)is shown to be removed prior to formation of dielectric material 220.The material 220 is ultimately utilized as gate dielectric, and material218 may not be suitable as gate dielectric. In alternative embodiments,material 218 may remain as dielectric 220 is formed so that thedielectric 220 covers only portions of material 12 that are not coveredby material 218.

Dielectric 220 may comprise any suitable composition or combination ofcompositions; and may, for example comprise, consist essentially of, orconsist of silicon dioxide. Dielectric 220 may be formed by thermaloxidation of exposed surfaces of semiconductor material 12, and/or maybe formed by deposition.

The wide portions of line 211 are shown converted to conductive material(as indicated by the cross-hatching) to form transistor source/drainregions 231 and 233. Such conversion may be accomplished by implantingconductivity-enhancing dopant into the material 12 of the line. Althoughthe conversion is shown occurring after removal of the masking material204 (FIGS. 32-35), it is to be understood that the conversion may alsooccur prior to the removal of such masking material. Alternatively, theconversion may occur at a processing step subsequent to that of FIGS.36-39.

The narrow region of line 211 may be appropriately doped with athreshold voltage dopant so that the narrow region corresponds to atransistor channel region 235 between the source/drain regions 231 and233.

Transistor gate material 232 is formed within the openings 216 and alsoover the narrow region 206 of line 211; and insulative material 234 isshown formed over the wide portions of line 211 on opposing sides of thegate material. Line 211 is shown in dashed-line view in the top view ofFIG. 36 to indicate that it is beneath materials 232 and 234. Otherstructures of construction 200 are similarly indicated in dashed-lineview in the top view of FIG. 36.

Gate material 232 may comprise any suitable composition or combinationof compositions, and in some embodiments will comprise, consistessentially of, or consist of one or more of metal, metal-containingcompositions and conductively-doped semiconductor material (such asconductively-doped silicon). If the gate material comprisessemiconductor material, such material may be referred to as a secondsemiconductor material to distinguish it from the first semiconductormaterial of base 12. The gate material may be part of a wordline whichextends substantially orthogonally to the line 211.

Insulative material 234 may comprise any suitable composition orcombination of compositions; and may, for example, comprise, consistessentially of, or consist of one or both of silicon dioxide and siliconnitride.

FIG. 38 shows that the gate material 232 entirely surrounds an outerperiphery of the narrow portion of line 211, and encircles the channelregion 235. The source/drain regions 231 and 233, channel region 235,and gate material 232 together form a field effect transistor. Suchfield effect transistor has an outer periphery of the channel regionfully encircled by gate material in at least one cross-sectional view(for instance, the view of FIG. 38).

FIGS. 36-39 show a single transistor along line 211. It is to beunderstood, however, that multiple transistors may be formed along theline. FIG. 40 diagrammatically illustrates an example of suchembodiment. Specifically, the figure shows a construction 300 comprisinga line 302 similar to the line 211 discussed above. The constructionalso includes isolation regions 301 analogous to the isolation regions202 of FIGS. 36-39.

Line 302 comprises wide portions 304 and narrow portions 306.Source/drain regions (not shown) may be within the wide portions, andchannel regions (not shown) may be within the narrow portions.

The line 302 is shown to be under alternating materials 232 and 234(with the line 302 being shown in dashed line view to indicate that itis under other materials). Material 232 and 234 are the gate materialand electrically insulative material discussed above with reference toFIGS. 36-39. The narrow regions 306 of line 302 are surrounded by gatematerial 232 analogously to the embodiment shown in FIG. 38.

An insulative material 310 is shown cutting through the wide regions ofline 302 to isolate source/drain regions of adjacent transistors fromone another. Material 310 may comprise any suitable composition orcombination of compositions; and may, for example, comprise, consistessentially of, or consist of silicon dioxide.

FIG. 41 illustrates an embodiment of a computer system 400. Computersystem 400 includes a monitor 401 or other communication output device,a keyboard 402 or other communication input device, and a motherboard404. Motherboard 404 can carry a microprocessor 406 or other dataprocessing unit, and at least one memory device 408. Memory device 408can comprise an array of memory cells, and such array can be coupledwith addressing circuitry for accessing individual memory cells in thearray. Further, the memory cell array can be coupled to a read circuitfor reading data from the memory cells. The addressing and readcircuitry can be utilized for conveying information between memorydevice 408 and processor 406. Such is illustrated in the block diagramof the motherboard 404 shown in FIG. 42. In such block diagram, theaddressing circuitry is illustrated as 410 and the read circuitry isillustrated as 412.

Processor device 406 can correspond to a processor module, and containvarious of the memory and isolation structures described above.

Memory device 408 can correspond to a memory module, and can comprisevarious of the memory and isolation structures described above.

FIG. 43 illustrates a simplified block diagram of a high-levelorganization of an electronic system 700. System 700 can correspond to,for example, a computer system, a process control system, or any othersystem that employs a processor and associated memory. Electronic system700 has functional elements, including a processor 702, a control unit704, a memory device unit 706 and an input/output (I/O) device 708 (itis to be understood that the system can have a plurality of processors,control units, memory device units and/or I/O devices in variousembodiments). Generally, electronic system 700 will have a native set ofinstructions that specify operations to be performed on data by theprocessor 702 and other interactions between the processor 702, thememory device unit 706 and the I/O device 708. The control unit 704coordinates all operations of the processor 702, the memory device 706and the I/O device 708 by continuously cycling through a set ofoperations that cause instructions to be fetched from the memory device706 and executed. Various components of system 700 can include one ormore of the memory and isolation structures described above.

FIG. 44 is a simplified block diagram of an electronic system 800. Thesystem 800 includes a memory device 802 that has an array of memorycells 804, address decoder 806, row access circuitry 808, column accesscircuitry 810, read/write control circuitry 812 for controllingoperations, and input/output circuitry 814. The memory device 802further includes power circuitry 816, and sensors 820, such as currentsensors for determining whether a memory cell is in a low-thresholdconducting state or in a high-threshold non-conducting state. Theillustrated power circuitry 816 includes power supply circuitry 880,circuitry 882 for providing a reference voltage, circuitry 884 forproviding a first wordline with pulses, circuitry 886 for providing asecond wordline with pulses, and circuitry 888 for providing a bitlinewith pulses. The system 800 also includes a processor 822, or memorycontroller for memory accessing.

The memory device 802 receives control signals from the processor 822over wiring or metallization lines. The memory device 802 is used tostore data which is accessed via I/O lines. At least one of theprocessor 822 or memory device 802 can include various of the memory andisolation structures described above.

The various electronic systems can be fabricated in single-packageprocessing units, or even on a single semiconductor chip, in order toreduce the communication time between the processor and the memorydevice(s).

The electronic systems can be used in memory modules, device drivers,power modules, communication modems, processor modules, andapplication-specific modules, and may include multilayer, multichipmodules.

The electronic systems can be any of a broad range of systems, such asclocks, televisions, cell phones, personal computers, automobiles,industrial control systems, aircraft, etc.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method of forming a transistor, comprising: providing asemiconductor material; defining a line across the semiconductormaterial, the line having a narrow region between wide regions, the linehaving a pair of opposing sides; forming a pair of trenches alongopposing sides of the line; forming protective material along sidewallsof the trenches to narrow the trenches; isotropically etching thesemiconductor material through the trenches to merge the trenches underthe narrow region without merge the trenches under the wide regions;forming gate dielectric along the narrow region of the line; formingelectrically conductive gate material within the trenches and under thenarrow region; conductively-doping the wide regions of the line of thesemiconductor material to form a pair of source/drain regions; such pairof source/drain regions being spaced from one another by a channelregion comprised by the narrow region of the line of the semiconductormaterial; wherein the narrow portion of the line has an outer periphery;and wherein the gate material is a transistor gate entirely surroundingthe outer periphery of the narrow portion of the line.
 2. The method ofclaim 1 wherein the protective material is removed prior to forming thegate dielectric; and wherein the gate dielectric is formed to entirelysurround the narrow region of the line.
 3. The method of claim 1 whereinthe semiconductor material is monocrystalline silicon, and wherein thegate material comprises at least one composition selected from the groupconsisting of metal, metal compounds, and conductively-dopedsemiconductor material.
 4. The method of claim 1 wherein the gatematerial comprises conductively-doped semiconductor material formed by:depositing semiconductor material within the merged trenches; and insitu doping the semiconductor material as it is deposited within themerged trenches.
 5. The method of claim 1 wherein the gate materialcomprises conductively-doped semiconductor material formed by:depositing semiconductor material within the merged trenches; andimplanting conductive-enhancing dopant into deposited semiconductormaterial.